From a7de684e1b6f460aae7d4dbf2568cb21130ec520 Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Thu, 1 Dec 2022 17:24:23 -0800 Subject: [PATCH] cmd/compile/internal/noder: stop creating TUNION types In the types1 universe under the unified frontend, we never need to worry about type parameter constraints, so we only see pure interfaces. However, we might still see interfaces that contain union types, because of interfaces like "interface{ any | int }" (equivalent to just "any"). We can handle these without needing to actually represent type unions within types1 by simply mapping any union to "any". Updates #57410. Change-Id: I5e4efcf0339edbb01f4035c54fb6fb1f9ddc0c65 Reviewed-on: https://go-review.googlesource.com/c/go/+/458619 Run-TryBot: Matthew Dempsky Reviewed-by: Keith Randall TryBot-Result: Gopher Robot Reviewed-by: Keith Randall --- src/cmd/compile/internal/noder/reader.go | 32 +++++++++++++++++++----- test/typeparam/issue52124.go | 4 ++- 2 files changed, 29 insertions(+), 7 deletions(-) diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go index bdec467f90..ac6d2fa931 100644 --- a/src/cmd/compile/internal/noder/reader.go +++ b/src/cmd/compile/internal/noder/reader.go @@ -519,13 +519,33 @@ func (r *reader) doTyp() *types.Type { } func (r *reader) unionType() *types.Type { - terms := make([]*types.Type, r.Len()) - tildes := make([]bool, len(terms)) - for i := range terms { - tildes[i] = r.Bool() - terms[i] = r.typ() + // In the types1 universe, we only need to handle value types. + // Impure interfaces (i.e., interfaces with non-trivial type sets + // like "int | string") can only appear as type parameter bounds, + // and this is enforced by the types2 type checker. + // + // However, type unions can still appear in pure interfaces if the + // type union is equivalent to "any". E.g., typeparam/issue52124.go + // declares variables with the type "interface { any | int }". + // + // To avoid needing to represent type unions in types1 (since we + // don't have any uses for that today anyway), we simply fold them + // to "any". As a consistency check, we still read the union terms + // to make sure this substitution is safe. + + pure := false + for i, n := 0, r.Len(); i < n; i++ { + _ = r.Bool() // tilde + term := r.typ() + if term.IsEmptyInterface() { + pure = true + } + } + if !pure { + base.Fatalf("impure type set used in value type") } - return types.NewUnion(terms, tildes) + + return types.Types[types.TINTER] } func (r *reader) interfaceType() *types.Type { diff --git a/test/typeparam/issue52124.go b/test/typeparam/issue52124.go index a113fc7444..07cba47982 100644 --- a/test/typeparam/issue52124.go +++ b/test/typeparam/issue52124.go @@ -6,7 +6,9 @@ package p -type I interface{ any | int } +type Any any + +type I interface{ Any | int } var ( X I = 42 -- 2.48.1